Integrated circuit devices such as transistors are formed over semiconductor wafers. The devices are interconnected through metal lines and vias to form functional circuits. In the formation of the metal lines and vias, a dielectric layer is etched to form through holes. The etching of the dielectric layer may involve a metal hard mask. Metal hard mask can be used in etching process to transfer patterns onto the semiconductor wafers. The metal hard mask can provide a desired etching profile and critical dimension control for decreasing geometries.